The invention relates to a method of projection spectroscopy for N-dimensional (N≧3) NMR experiments with the following steps:
Data Recording Comprising                (a) selection of N-dimensional NMR experiments out of a group of N-dimensional experiments, selection of the dimensionalities of the projections and unconstrained selection of j sets of projection angles, with j≧2,        (b) recording of discrete sets of j projections from the N-dimensional NMR experiments at the selected projection angles,        (c) peak picking and creating a peak list for each of the j projection spectra.        
A method of this type is known from reference [40] listed below).
In NMR studies of biological macromolecules in solution (see reference [1-4] as listed below), multidimensional NMR data are commonly acquired by sampling the time domain in all dimensions equidistantly at a resolution adjusted to the populated spectral regions (see reference [5] as listed below). With recent advances in sensitivity, due to high field strengths and/or cryogenic detection devices, the time required to explore the time domain in the conventional way typically exceeds by far the time needed for sensitivity considerations, so that the desired resolution in the indirect dimensions determines the duration of the experiment. In this situation of the “sampling limit”, which is common in 3- and higher-dimensional experiments with small and medium-size proteins (see reference [6] as listed below), the desired chemical shift information has been collected using “unconventional” experimental schemes, such as non-uniform sampling of the time domain (see reference [7,8] as listed below) or combination of two or more indirect dimensions (see reference [9,10] as listed below).
The concept of combining indirect dimensions has lead to reduced-dimensionality experiments (see reference [9] as listed below) and G-Matrix Fourier transform (GFT) NMR (see reference [11, 12] as listed below). In GFT-NMR, several evolution periods of a multidimensional NMR experiment are combined, the data are processed using a G-matrix, and the resulting set of spectra is analyzed jointly to is identify the peaks that arise from the same spin system and to calculate their resonance frequencies (see reference [11] as listed below). In another approach, projection-reconstruction (PR-) NMR (see reference [13-16] as listed below), the projection—cross-section theorem (see reference [17, 18] as listed below) is combined with reconstruction methods from imaging techniques (see reference [19, 20] as listed below). In particular, a scheme for quadrature detection along tilted planes in the time domain allows the direct recording of orthogonal projections of any multidimensional experiment at arbitrary projection angles (see reference [15] as listed below). In PR-NMR, the full multidimensional spectrum is then reconstructed from the projections of the multidimensional spectral data (see reference [13-16] as listed below).
The analysis of complex NMR spectra typically involves intensive human interaction, and automation of NMR spectroscopy with macromolecules is still in development. Thereby the distinction of real peaks from random noise and spectral artifacts, as well as peak overlap represent major challenges (see reference [21-23, 40] as listed below).
The known methods show disadvantages like limitations on the possible number of projection angles and the requirement of manual interaction during operation. Further current automated methods can only handle the case N=3 and do not allow an easy extension to higher dimensions.
It is an object of the present invention to overcome the described disadvantages and to propose a reliable method of automated projection spectroscopy without restrictions on projection angles and dimensionality.